This invention relates to telephony networks and to methods of signalling.
Data traffic has been growing at unprecedented rates over the last few years in both the corporate and the residential sectors. The introduction of the Internet to the general public has generated an increased demand for higher-speed access from residences across network. The business community has not only seen growth in data traffic but also experienced a diverse change in service requirements.
The demand for data services has resulted in the proliferation of Internet Service Providers (ISP) deploying high bandwidth networks. As the competition between them increases, the ISPs are beginning to carry voice traffic over their networks, and will bundle data and voice services to increase account control on end-users. They are thus entering into direct competition with traditional telephone service-providers whose voice networks are being overwhelmed by the explosion of data traffic over a narrow band Time Division Multiplexed (TDM) network infrastructure that was not intended for, nor is capable of supporting such dramatic changes in traffic patterns and capacity.
In the United States, the 1996 Telecommunications Act has far-reaching implications on how telecommunications will be offered in the future. Local Exchange Carriers (LEC) now have the opportunity to enter new markets and generate new revenue streams by expanding their voice service portfolio to include long distance services and out-of-region local services. From a network implementation perspective, the traditional incumbent service providers (LECs) have the opportunity in new market segments, to deploy new networks specifically designed and engineered to satisfy the new broadband requirements of their customers. However, at the same time there will also be increased pressure on the incumbent service-providers to protect their existing market base from new entrants attempting to target their prime customers in major urban centers where extensive TDM based narrow band networks are in existence. New entrants will differentiate their services by offering lower cost, faster deployment, and enhanced service capabilities through advanced broadband architectures such as Asynchronous Transfer Mode (ATM). In order to defuse this competitive threat, there is a need for incumbent service-providers to cost effectively enhance their TDM based narrow band networks to achieve similar efficiencies, bandwidth capabilities and service flexibility.
A current standard (International Telecommunication Union-Telecommunication Standardization Sector Recommendation Q.2660) specifies how service providers shall provide signalling protocol conversion functionality at the interface between their existing TDM narrow band network and an ATM broadband network. The recommended protocol conversion is between the existing ISUP protocol currently used in Common Channel Signaling number 7 (CCS7) for call connection and call control, and the new Broadband ISUP (B-ISUP) protocol intended for use with ATM networks. Current versions of the B-ISUP protocol lack many of the call parameters available to ISUP and which are required by many voice services offered today. If this was the only problem associated with protocol conversion, industry could simply enhance and evolve B-ISUP to include all the call parameters of the existing ISUP protocol. However, protocol conversion becomes challenging as very often there are many different versions of the same protocol; for example to meet individual country requirements. This introduces complexity and expense at the vendor level, service providers level and even the installer level in ensuring that the correct protocol conversion is occurring at the right place. Another potential problem area for service providers is that even though B-ISUP may be a standards protocol it will likely not be ubiquitous throughout ATM networks. As B-ISUP has been modeled for telephony it is not likely to be ubiquitous for the simple reason that many ATM networks will be designed and installed solely for data and hence will not therefore have a requirement for all the features and complexity of B-ISUP.
Conversion to other protocols such as the ATM Private Node to Node Interface (PNNI) protocol would not be desirable at this point in time since it does not support the telephony features of ISUP.
The invention seeks to provide an improved method of signaling.
In accordance with one aspect of the invention there is provided a method of signaling in a system comprising a broadband network, a narrow band network containing an originating and terminating switching node interconnected through a signaling network for processing call control messages between the originating and terminating switching nodes, an originating and terminating network access point at the boundary of the narrow band and broadband networks, for respectively interfacing the originating and terminating switching nodes to the broadband network, and mapping and translatioin means connected to the originating switch, signaling network and originating network access point, the method comprising the steps of: sending a call control message over the narrow band netwok from an originating switch to a terminating switch, the call control message having a narrowband trunk identifier to indicate to the terminating switch a trunk for receiving corresponding call related data; and in response to the narrowband network call control message, sending the narrowband trunk identifier through the mapping and translating means and over the broadband network, from the originating network access point to the terminating network access point, for use by the terminating network access point in mapping call related data to the trunk corresponding to the trunk identifier.
Preferably, the broadband network is an asynchronous transfer mode (ATM) broadband network and the signaling network is a common channel signaling system number 7 (CCS7).
More preferably, the step of sending the narrowband trunk identifier over the broadband network comprises inserting the trunk identifier into the Calling Party Sub-Address Information Element of the Sub-Address Field of an ATM setup control message. Additionally, the narrowband trunk identifier comprises the originating point code, destination point code and the originating circuit identification code contained in an ISUP initial address message.
Significant advantages are realized through through such a network system. Service providers, for example incumbent local exchange carriers (ILECs) now have access to BB connectivity while retaining the use of the extensive CCS7 signalling networks and Advanced Intelligent Networks resources. Investment in the CCSand signaling infrastructure is hence not lost and the proven robustness and reliability of these networks is retained. Local exchange carriers can continue to take advantage of Intelligent Network capabilities in providing a large variety of voice services, but also to make available some of the current service features for future BB services. Further more each network is virtually independent of each other and can evolve as such. Telephony service call related signaling is kept separate from the broadband network connectivity signaling thus allowing service providers to evolve their service specific signaling requirements independently of whatever BB networks are used now or in the future.